This invention relates to improvements to the variable speed tractive transmission of U.S. Pat. No. 3,673,881, Burke, July 4, 1972, Cl 74-198, 74-200.
In this transmission variation of speed ratio is achieved by tilting the rotational axis of an intermediate ring member while the ring is in tractive contact with driving and driven members. The location of the pivot axis about which the ring is tilted has an effect on the ease and smoothness with which the ring can be moved, and therefore upon the sensitivity of speed control. It is the first object of this invention to define favorable locations for said pivot axis.
In the patent cited above, embodiments are described which permit power input and output shafts to appear at the same or at opposite ends of the transmission. In the latter case the thrust between the driving and driven tractive members is carried by the transmission casing and the moments caused by the thrust have been found to require that each shaft be supported on bearings that are spaced widely apart, both of which comprise thrust bearing capability. This bulky and complicated structure can be made more rigid and compact by mutually supporting the tractive members, each by the other and by transfer of axial force between them by a single thrust bearing. It is therefore a second object of this invention to provide an arrangement of parts which will simplify construction of the transmission for applications which require input and output shafts to be at opposite ends of the casing.